Process for the conversion of high-boiling hydrocarbons into low-boiling hydrocarbons



March 6, 1928.

OCARBONS L. EDELEANU PROCESS FOR THE CONVERSION OF HIGH BOILING HYDEHYDROCARBONS INTO LOW BOILING Filed June 28. 1926 bmw,

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Patented Mar. 6, 1928.

UNITED STATES PATENT OFFICE.-

LAZLB EDELEANU, OF BERLIN-CHARLOTTENBURG, GERMANY, ASSIGNOB TO ALLGE-MEINE GESELLSCHAFT FUR CHEMISCHE INDUSTRIE, F BERLIN, GERMANY.

PBbC'ESS FOR THE CONVERSION OF HIGH-BOILIN G HYDROCARBONSINTOT-OW-BOILING HYDROCARBONS.

Application filed June as, 1926. Serial No. 119,242.

My invention comprises a treatment of petroleum distillates prior totheir further fractional distillation by the cracking process, by whichtreatment objectionable byproducts are eliminated or reduced in quantityand a higher proportion of commercially valuable products secured. I

The known cracking processes which consist in the conversion ofhydrocarbons of 1 high boiling point into those of low boiling point,increase the yield of light distillates in the fractional distillationof crude oil, at either atmospheric or increased pressure, by causingthe oil vapors to remain in contact with the superheated metallicsurface of the still. The su erheating of the oil vapors causes asplitting of the high boiling hydrocarbons, eonvertmg them into lowerboiling hydrocarbons. Under very high tem erature, the splitting of themolecules 0 the hydrocarbons is pushed too far, resulting in theformation of fixed gases and a large amount of coke, in addition to thelight hydrocarbons. M

Based on'these facts a great number of processes have been devised forproducing gasoline from the hi h boiling hydrocarbons which processesiifer only in the 0011- ditions under which temperature and pressure areapplied, or in the arrangement of the equipment in which the cracking iscarried out.

All of these processes have certain drawbacks in common, which reactunfavorably on their commercial value for producing gasoline from highboiling hydrocarbons. The main disadvantages are:

The asphaltum and the substances rich in carbon always present in thecracking stocks,

produce during the cracking operation, a

largeamount of coke which adheres to the walls of the apparatus. Itsremoval is dif-- ficult and necessitates frequentshutting .down of thestill for cleaning. "The residuum 4 oil which has not entered into thereaction and which remains as. a by-product generphur dioxide prior tosubmitting it to the cracking process. It is knownthat the sulphurdioxide is a good solvent for tlie"nitrogen and sulphur bearingcompounds as well as for asphaltum and substances rich in carbon.Separation of these injurious sub-. stances by liquid sulphur dioxideremoves the causes of the disadvantages enumerated above.

Methods of treatment of petroleum oils with liquid sulfur dioxide forremoving substances soluble therein are described in my United StatesPatents Nos. 911,553 and 1,526,665. A preferred method is illustratedin'the accompanying drawing, showing diagrammatically an arrangement ofapparatus suitable forearrying out the invention.

Referring to the drawing, the untreated cracking stock is supplied froma convenient source, shown as the tank 1, to a pump 2 by which it ispassed through a precooler 3 and the cooler 4 to the lower part of themixer 5. Both the precooler 3 and the cooler 4 are of the double pipetype. As a low temperature in the mixer 5 is desirable, the cracking oilshould be well cooled before entering the mixer 5. In the precooler 3the oil is precooled by the cold treated oil leaving the mixer 5, and inthe cooler 4 it is cooled to the desired low temperature by means ofevaporating sulfur dioxide. 6

The liquid sulfur dioxide re uired for the treatment of the cracking oiis supplied from a storage tank 6 and passed through a precooler 7of thedouble pipe type to the cooler 8. In the precooler 7 the sulfur dioxideis precooled by the cold extract consisting of liquid sulfur dioxidewhich has dissolved constituents of the oil after leaving the mixer 5;in the cooler 8 it is cooled by evaporating a part of itself at lowpressure. This cold sulfur dioxide is taken by a pump 9 and passed tothe top of the mixer 5.

The process of mixing the oil and the sulfur dioxide is a continuousone.

The oil passing through the mixer 5 first dissolves the sulfur dioxide.As soon as the oil is saturated, the sulfur dioxide is extracting theheavy hydrocarbon from the oil. This extract is settling in the lowerpart of the mixer 5 and drawn off into the extract tank 10. The refinedoil is drawn off from the upper part of the mixer 5 into the refined oiltank 11.

The extract is taken from the extract tank 10 by the pump 12 and passedthrough the precooler 7 and preheater 13 to the evaporators 14, 15 and16. In the precooler 7 the extract is precooling the sulfur dioxide,heating up itself. In the preheater 13 the extract is heated to a highertemperature by the finished hot' extract leaving the last evaporator 16.

In the evaporator 14 the sulfur dioxide contained in the extract isevaporated by heating, by means of heating pipes 25, and passes to thecondenser 17, where it is condensed. As the sulfur dioxide contained inthe extract cannot be expelled completely only by heating, the remainingextract is passed to the vacuum evaporators 15 and 16 after the greaterpart of the sulfur dioxide in the first evaporator has been removed; in

. the vacuum evaporators 15 and 16 the last traces of sulfur dioxide aredrawn off by the sulfur dioxide gas pump 26 and vacuum pump 27 andforced into the condenser 17.

The refined oil is taken from the raffinate tank 11 by the pump 28 andpassed throu h the precooler 3 and the preheater 18 to t e evaporator-s19, 20 and 21. In the precooler 3 the rafiinate is precooling theuntreated cracking stock, heatin up itself, and in the preheater 18 therafiinate is heated to a higher temperature by the finished rafiinatecoming from the last evaporator 21.

In the evaporator 19 the sulfur dioxide dissolved in the refined oil isremoved mainly by means of heating pipes 24, the last traces of sulfurdioxide are drawn off by gas pump 26 and vacuum pump 27 from the vacuumevaporators 20 and 21.

The finished hot extract is discharged from the last evaporator 16 bythe pump 22 and passed through the preheater 13 to the storage tank. Inthe preheater 13 the finished extract is heating up the extract going tothe first evaporator 14 at the same time cooling down itself.

The finished hot rafiinate is taken from the last evaporator 21 by thepump 23 and passed through the preheater 18 to the storage tank. In thepreheater 18 the finished raffinate is heating up the raftinate going tothe first evaporator 19 and at the same time cooling itself down.

The vacuum pump 27 draws off the last traces of sulfur dioxide from thelast evaporators 16 and 21 under high vacuum and pushes the vapors tothe gas pump 26.

The gas pump 26 draws off that part of sulfur dioxide which cannot bedriven out only by heating, from the evaporators 15 and 20. At the sametime it draws o fi vapors of sulfur dioxide from the cooler 8. Itcompresses all the vapors and pushes them to the condenser 17 in whichthey are liquefied.

The liquid sulfur dioxide is collected in the tank 6 and used again.

For cooling the cracking stock, part of the liquid sulfur dioxide isbranched off before entering the cooler 8 and passed through the c0010!4. In the cooler 4 the liquid sulfur dioxide comes in contact with thecracking stock having a higher temperature than the sulfur dioxide and apart of the sulfur dioxide vaporizes at a rather low temperature as thepressure is kept low at the sulfur dioxide side. Thus the cracking stockpassing the cooler is cooled to the desired temperature.

The vapors of sulfur dioxide are drawn off through the cooler 8 to thegas pump 26.

As one illustration of the advantages of my invention I give thefollowing: By the treatment with llquid sulphur dioxide of a TexasLuling gas oil having a specific gravity of 0.889 and a sulphur contentof 0.8%, a gas oil with a specific gravity of 0.865 and sulphur contentof 0.24% is obtained. If both gas oils are cracked separately underequal conditions of pressure (about 85 lbs.) and temperatures (about 770F.) the following products result:

Non-

treated Treatfid gas oil 0 P21 cent P I Cracked distillate n 6 Gasoline4!) 53. 7 Coke 4. G i. 5 Sulphur in the cracked distillate 0. 34 0.09Sulphur in gasoline 0. l 0. 06

In non-treated gas oil which remains as a by-product there will formafter a while a sediment of about 6% of carbon and asphaltic matter,while in the treated gas oil there will appear only traces of sediment.

If the cracking of gas oil into gasoline is affected by pressureandcatalytic action, as for instance by means of any of the knowncatalysts for aiding in the conversion of hydrocarbons, the advantagesof using a gas oil preliminarily treated with liquid sulphur dioxide aremore striking.

The invention is not restricted to any particular oil or crackingprocess but pertains generally to the use of liquid sulphur dioxidefortreetingthematerialsto' cracked prior to subjecting them-to What-Iclaim is:

v 1. An im roved recess for the cracking 5 of high boi ng hy inghydrocarbons which consists in'submitting to a p cracking process theportion of-the distillats which remains undissolved after being treatedwith liquid sul- I phur dioxide. v

2. An im roved process for the cracking of high hydrocarbons into lowboiling hydrocarbons by removing from the cracking st'ockthe-.nitrogenand sulphur com- 15 pounds as well as the asphaltum bymeansof v rbons into low boil-- li uid sulphur dioxide and by afterwardsmitting the cracking 'stockto a pressure cracking process. n

3. An improved process for cracking hydrocarbons aving a high boilingpoint into hydrocarbons having a lower boiling point b3 treating themwith li uid sulphur dioxi e, separating the li sulphur dioxide andhydrocarbons dim ved therein, and subjecting the undissolvedhydrocarbons to pres- 2 sure cracking in the presence of a catalyst.

Intestiinony whereof, I have signed my name to this specification. 1

LAZAR EDELEANU.

